1. Field of the Invention
The invention relates to a liqueur or alcohol-containing beverage comprising as ingredients cream, yoghurt or another dairy product, obtained by mixing the dairy product with alcohol or an alcohol-containing liquid, flavouring agents, colouring agents, emulsifiers, stabilizers, sugars or artificial sweetening agents, fats, acids and further conventional ingredients.
Such liqueurs are known from the following patents.
2. Description of Related Art
British patent application GB 2 084 185 discloses the preparation of cream liqueurs on the basis of cream, sugar alcohol, sodium caseinate, flavouring and colouring agents, which comprises adding citrates to improve their stability by binding calcium.
Japanese patent application JA 56/193036 discloses the preparation of cream liqueurs from non acidulated cream, alcohol, sugar and flavouring agents which comprises adding a surfactant, e.g., sodium caseinate, to increase their stability.
European patent application EP 0 067 592 discloses the preparation of cream liqueurs of the same composition as described in JA 56/193036, the surfactant added thereto in connection with their stability being, in addition to a sodium caseinate, an emulsifier having an HLB value of less than 12.
U.S. Pat. No. 4 419 378 discloses the preparation of similar cream liqueurs as described in EP 0 067 592, but without sodium caseinate and with a surfactant having an HLB value of more than 10, to increase their stability.
British patent application GB 2 145 111 discloses the preparation of cream liqueurs of the same composition as described in the above publications, which comprises adding sodium or potassium citrate to increase the emulsion stability, as is known from the older publication GB 2 084 185.
European patent application EP 0 177 077 discloses the preparation of yoghurt liqueurs, which comprises mixing a mixture of fermented or acidulated milk having a pH of 5-3.5 with sugars, flavouring agents, thickening agents and the like, then homogenizing in a special manner and heating to increase the bacteriological stability, followed by admixing alcohol.
British patent application GB 2 176 088 discloses the preparation of powders comprising sodium caseinate,starch or starch syrup, emulsifier and skim milk powder with 58-62% fat of dairy or other origin, said powders, when mixed with sugar, alcohol and water in a household mixer, being capable of providing a cream liqueur, on which few further stability requirements are imposed. The long term stability of the product is based on the fact that a dry powder does not change its properties after its preparation any more than sugar or a strongly alcoholic liquid, and the total beverage can be consumed immediately after mixing these ingredients with water.
As appears from these publications, stability of these dairy liqueurs is generally a problem showing many different aspects. Thus, for instance, the product may be unstable owing to the fact that during storage the viscosity increases even to such an extent that the liqueur gels and cannot be poured out of the bottle anymore. Also, the product may show creaming caused by a fatty layer formed on top of the liquid in the bottle. Or even a more or less clear layer of liquid or whey may separate at the bottom. Furthermore, a precepitate or sediment may be formed, a fat collar may be formed in the neck of the bottle, or more in general, the liqueur may tend to show a non-homogeneous appearance caused by a combination of these deficiencies. Colour and flavour may also change in the course of time, and in general, such a change therefore means a deterioration. It is often possible to remove such deficiencies by selecting suitable emulsifiers, antioxidants, thickeners and stablilizers, or by a proper selection of such ingredients using a special process in which especially the method of heating and homogenizing plays an important part. Considered in itself, a yoghurt liqueur or a cream liqueur is a very complicated colloidal system in which all kinds of counteracting factors play a part. Thus, for instance, in a dairy product the fat will be stabilized to a rather homogeneous and stable emulsion by means of the milk proteins which ipso facto are also colloidally dispersed in micellar form.
When alcohol is added to milk, it mixes with the aqueous phase, but as a result the character of that aqueous phase will also change considerably. Consequently, the protein micelles may be destabilized, and this, in turn, influences the stability of the fat emulsion. For this reason it may be necessary to add emulsifiers to the milk or cream in order to maintain the fat emulsion, and in general, mechanical homogenization will be required to reduce that emulsion in order to inhibit creaming.
For the purpose of avoiding flocculation of protein, stabilizers may be added, such as thickeners or protein-reactive esters, such as sodium stearoyl lactylate. A reduction of the pH in the preparation of yoghurt liqueurs also produces a strong effect on the stability of the colloidal system, because the pH reduction causes the protein to tend to flocculation owing to approach of the isoelectric point. This has an indirect effect on the stability of the fat emulsion.
In order to obtain a stable liqueur, the product must be heated to kill undesirable microorganisms, and in addition to the destabilization caused by alcohol and by pH reduction, the stability is once more disturbed substantially owing to this heating.
In well-known processes one or more of these stability aspects are influenced in different ways by appropriately selecting raw materials and techniques.
In general, all these improvements of the stability are concerned with the stability of the bottled product, as it reaches the customer in the closed bottle. But then new quality problems arise, particularly if the consumer consumes only a part of the contents of the bottle and wants to store the rest until a later time. The contents of the bottle come into contact with fresh air containing oxygen, which promotes oxidative spoilage. Similarly, bacteria and other microorganisms may get into the liqueur and become activated.
While the presence of alcohol inhibits the activity of microorganisms and even causes living bacteria to be killed, the activity of the enzymes produced by bacteria present in the raw materials is not stopped by alcohol. A pasteurizing or, anyhow, enzyme-inhibiting heat treatment, germ-deficient bottling and storage in closed bottles are means for avoiding spoilage in this respect. Also, exclusion of air and protection from light may be important to avoid changes of colour and flavour. Oxidation of flavouring agents is influenced by oxygen and light, so that the product is preferably stored in a closed bottle or jug as long as possible, before it is used.
But once the bottle has been opened, so that the product comes into contact with oxygen from the air, a new type of stability problem arises from the fact that the previously stable product may change its flavour, colour and further proporties within a short period of time. Particularly the flavour of liqueurs on the basis of yoghurt or other types of fermented milk is very sensitive to oxidation by the action of air oxygen. A means for avoiding that deterioration is to replace butterfat by a fully saturated fat, e.g., a hardened vegetable fat. Another means for delaying that deterioration is to store the opened bottle in a refrigerator. But it has been found that this means is not without its drawbacks because, on the one hand, the deterioration is only delayed so that after some time flavour deficiencies will occur notwithstanding, while,on the other hand, another deficiency will become apparent when an oxidation-stable, hardened fat is used in a liqueur.
As a matter of fact, storage at temperatures about 5.degree. C. and less shows that a clot is easily formed within the neck of the bottle, the homogenous emulsion of the liqueur is disturbed, and a disturbing clustering takes place. This results in that the appearance of the liqueur is damaged, the pouring out is impeded, and in addition, the flavour impression of a beverage with clots is not appreciated by the consumers.